Tuesday22 August 2017

Drawing board: Sita UK energy-from-waste facility by Grimshaw

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Great Blakenham in Suffolk will be the location for one of the many new energy from waste (EfW) facilities. Grimshaw partner Chris Nash and project architect Chris Fletcher discuss their design for the plant.

How did you secure the commission for this facility?

Chris Nash We were approached by Sita UK, a recycling and resource management company. There is a big market for energy from household waste in the UK at the moment and we’re very glad to be involved in this sector. There is a lot going on in it and it’s very competitive.

Sita appreciates the competitive advantage that we can bring through the quality of architecture over and above the technical merits of its bid. It is a very rewarding client.

What scope is there for architectural expression in such a process-led building?

CN As part of our research we went to see Sita’s plant in north London and also the Lakeside plant near Heathrow. There is a choice about whether you express each component of the process or whether you envelop all of them under one roof. We took the decision to represent each function in the process clearly. Otherwise, we would have had to enlarge the building. Instead we shrink-wrapped each part and used the skin of the main turbine hall to hone our response to the Suffolk setting.

It’s a fairly honest building. We don’t like hiding things or dressing them up as something else to make an architectural feature, as some architects have done with the chimneys on other energy-from-waste power stations. Our design shows how the building works through the various volumes, and in doing so, creates an architectural expression of its own.

I am enjoying our return to designing industrial buildings. Thirty years ago the practice was founded on award-winning industrial sheds such as the Herman Miller and Vitra factories and the Financial Times Print Works. We can bring a good clean and honest industrial architectural approach to the new wave of alternative energy generating buildings.

What was the biggest challenge?

Chris Fletcher How to orien-tate the building on the site, which is a brownfield former council works department with a lot of hard landscape.

We spent a long time working out how to position it and how to organise flow around the site, and came up with 16 variations of orientation with different access loops in order to minimise the impact of the building, which is 37.5m tall. We ended up with an east-west axis with an access loop running clockwise around the site, which backs on to the Gipping Valley.

How did you accommodate the many processes?

CN Waste lorries deliver domestic waste to the tipping hall. It is tipped into a 12m-deep pit before being craned up into the furnace. We’ve expressed a clean split between the tipping hall, crane, and boiler elements. The rest of the building is a foil to the main feature: the boiler room, which is the tallest part of the building. The chimney stacks are immediately next to the boiler hall and are as thin as they can be, clad in mill-finished aluminium so they are reflective enough to blend in with the sky.

The air-cooled condenser fans serving the turbine are in a building on stilts to help keep them cool by sucking in air from underneath and are connected by pipe to the main hall. The solid product from the furnace is incinerated bottom ash (IBA). This is processed and stored in a low level covered yard, concealed in an irregular shaped area behind the main building before being sold on for use in building products.

CF We took a lot of time to make sure the materials help blend the building into the countryside. We are expressing the buildings in a metal composite facade panel. There is a lot of established landscape around the site and combined with differences in level, we can effectively hide a lot of the facility including all of the ash storage building to the south. We’re returning about one-third of the site at the north end to soft landscaping and extended over this to form the visitor centre.

How will the power station respond to the landscape?

CN Suffolk has a broad landscape with this big sky around it and is also pretty wet, with reeds and marshes.

There are also lots of old industrial buildings around it such as Snape Maltings as well as very prominent church towers. We’re not confusing our building with a church, but its chimneys will be seen for miles.

The solid parts of the buildings are deliberately plain and dark in reference to Suffolk’s black barns. We’ve reserved all the fun and games for the big turbine hall, which will appear to glow at night.

A lot of people will see glimpses of the big volume of the turbine hall in passing from the road or train and we wanted to reflect the movement of the observer, and also the rippling effect of a field of grass in the wind through the patterns of the louvres. This introduces a degree of finesse to a large industrial building.

CF The Willis Faber building is just down the road in Ipswich and the local authority has said it is looking forward to a design that is a local response to the landscape but also a very contemporary modern building.

Aside from its core function, how sustainable will the power station be?

CF The client insisted on a Breeam Excellent rating, which we can achieve through a combination of how the building is set in the landscape and specification. It is steel-framed but we kept it as lightweight as possible. The building’s energy use is very low. It is self-serving and CHP-enabled, and in the day rooflights bring light into the hall. The offices and visitor centre are naturally cross-ventilated. Water will be harvested for use in the boiler room, grey-water flushing, and for fire-fighting if necessary.

What is the timetable for the project?

CN The planning application was submitted in January and is still in for consultation.

Sita hopes to open it in 2014. Creating the EfW facility will result in Suffolk County Council saving 75,000 tonnes of CO2 per year compared with landfill. CO2 will be emitted from the chimney, but this is preferable to the ground pollution and methane produced by landfill.

The electricity produced will power 30,000 homes and the ash can be used for things like road aggregate.

Designing the facade

Patterned panels will help the building fade into its surroundings

Without having to worry about insulation, Grimshaw had a great deal of freedom in the design of the 37.5m x 60m turbine hall facade. Acoustics were an issue and extensive noise testing was carried out to establish that noise from the plant would not impact on the surrounding community.

But otherwise, the walls simply have to function as containment to keep any dust inside.

However, the practice wanted the facade to do more in order to mitigate the bulk of the building and blend better into the landscape. The solution is a simple polycarbonate-skinned box clad in silvery blue metal louvres, each turned at a slight angle to each other so that when the light strikes it and moves across, it will appear quite dynamic. The angles and configuration of each 3m-long panel were worked out in cad animation to test opacity. In the final design, the series of panels is rotated by 90 degrees in a stepped sequence to give the appearance of continuous, 60m-long twisted louvres.

“It is set out in a chevron pattern and is at its most open at the highest point of the building,” says project architect Chris Fletcher.

More light is brought in through ETFE roof lights at the perimeter of the roof wall which serve to further help the building fade into the skyline.


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